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Jello Structures

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					Title: Jello Structures

Authors: Leslie Bucar, 7-12 Science Teacher, Fond du Lac Ojibwe School, B.S.
          Biology, B.A.S. Teaching Biology, B.A.S. equiv Teaching Chemistry
          Carolyn Olson, K-12 Art Specialist, AlBrook School ISD #2142, B.F.A.
          Studio Arts, B.F.A. equiv. Art Education, M.F.A. Painting

Objectives:
Observe how height and proximity affect structures during an earthquake.
Observe the effect of different stiffnesses in structures during an earthquake.

Grade Level: Middle School

Time: 30 Minutes- 1 Hour

Materials:
Jello of various colors
Hot water
Assorted sizes and shapes of molds to use for Jello
Shake table
Drill
Cookie sheet

Content Standards:
National:
Structure of the Earth System
Using Knowledge of Structures and Functions
Reflecting Upon and Assessing the Characteristics and Merits of Their Work and the
       Work of Others
Making Connections Between Visual Arts and Other Disciplines

Minnesota State:
History and Nature of Science 7-Scientific World View
History and Nature of Science 8- Scientific World View
History and Nature of Science 7-Scientific Inquiry
History and Nature of Science 8- Scientific Inquiry
Earth and Space Science 8-Earth Structure and Processes
Artistic Interpretation- Understand Structures
Artistic Creativity and Performance- Understand Structures and Incorporate Feedback to
        Revise Artistic Expression in Visual Art

Problem: In this lab, we will be modeling how earthquakes affect structures of
different heights and stiffness. How do you think stiffness and height will affect your
“buildings” in an earthquake?
Vocabulary:
Static load, dynamic force, oscillate, period, amplitude, natural period

Introduction:
         Most loads that a building must support, like the weight of the floors, walls, and
people inside, are applied slowly over time and are called the static loads. But the load
or the force of an earthquake is applied very quickly and is called the dynamic force.
         When things go side-to-side or up and down they are said to oscillate. The
oscillations of the ground near the epicenter of a quake are generally very violent and
quick. The time it takes to complete one cycle of up and down movement or side-to-side
movement is called the period of oscillation and it is especially short near the epicenter,
usually less than one second. As the seismic wave travels, the earth acts somewhat like a
shock absorber and it damps out the short-period vibrations, leaving long-period
vibrations. Both near and far from the epicenter, the prevailing vibrations are those with
the largest amplitude, or the largest difference from one side to the other or up and down.
         Structures that are different heights, weights, and made from different things will
respond differently to the shaking of the earth. A rigid structure will tend to move
together with the movement of the ground while a flexible structure will lag behind it.
The property that identifies rigid or flexible buildings is their natural period of vibration,
that is, how long it takes for a structure to complete a cycle of side-to-side movement
after the quake movements are over. Low buildings tend to be stiff and have short
natural periods, while tall buildings (with steel or concrete frames) tend to be flexible and
have long natural periods.




                                     Natural Period of Vibration on Tall vs. Short Building
                                      earthscience.org/…/geopro/seismic/seismic.html

Along a typical city street, buildings of different heights and construction are lined up
next to each other. In an earthquake, these buildings will vibrate with different periods
and different amplitudes, and if built too close together, may even bump into each other.
        Since buildings must be designed to anticipate earthquake shocks coming from
any direction, the plan of a structure affects its response to earthquake vibrations. A
structure with a “regular” plan (square, circular, triangular, or otherwise symmetrical),
will vibrate without twisting. A building with an irregular plan will both twist and move
sideways during an earthquake. Knowing how the shape of a structure will affect how it
acts in an earthquake helps architects and engineers design buildings and adaptations to
the structure to successfully resist a quake.
Hypothesis: Write your hypothesis using the problem here.

Procedure:
   1.  Drill four holes in the cookie sheet to line up with the holes on the shake table.
   2.  Prepare Jello according to package directions.
   3.  Pour Jello into different size and shape molds.
   4.  Label molds as “regular jello”
   5.  Put in refrigerator to cool.
   6.  Prepare more Jello according to package directions for Jigglers. (These will be
       our “stiffer” buildings.)
   7. Pour Jello into different size and shape molds.
   8. Label molds as “Jigglers”
   9. Put into refrigerator to cool.
   10. Screw cookie sheet into shake table.
   11. Arrange your “regular jello” city on one half of the cookie sheet. (To loosen Jello
       from the molds, run hot water over the mold and then invert onto the cookie
       sheet.) Make sure that at least two “high-rise” buildings are close to each other.
   12. Arrange your “Jiggler” city on the other half of the cookie sheet. (To loosen
       Jigglers from the molds, run hot water over the mold and then invert onto the
       cookie sheet.) Make sure that at least two “high-rise” buildings are close to each
       other.
   13. Turn on the shake table on low frequency.
   14. Make observations.
   15. Turn up the frequency.
   16. Make observations.
   17. Unscrew cookie sheet from shake table.
   18. Clean up!

Collecting and Analyzing Data:
   1. Fill in the table on the next page.




Conclusion:
   1. If you are in a crowded city like New York, and buildings have to be built close to
      each other, what could we do to keep them from bumping into each other?
           Teacher Lesson Guide and Key: Jello Structures
Collecting and Analyzing Data Key:
1. Fill in the table on the next page.
        Answers will vary.


Conclusion Key:
    1.    If you are in a crowded city like New York, and buildings have to be built close
         to each other, what could we do to keep them from bumping into each other?
         Design the buildings with the same natural frequency, connect them to make them
         “one”, tie them together.


Extension:
Before cleaning up the Jello Cities, allow students a chance to try and reinforce the
buildings against the quake. They could add things to the buildings like straws,
toothpicks, pipe cleaners, etc. Then re-run the shake table to see how their modifications
to the buildings affect how the buildings act in an earthquake.



Bibliography:
Levy, M. and Salvadori, M. 1995. Why the Earth Quakes. W.W. Norton and Company,
       New York.

Resources:
For a video of a “jello city” on a shake table:
www.exploratorium.edu/faultline/damage/building.html

For the website portfolio of the artist who created the Jello City:
 www.lizhickok.com

				
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